Sonoluminescence is a well-known phenomena discovered in the 1930's in which light is generated when a liquid is cavitated. Although a variety of techniques for cavitating the liquid are known (e.g., spark discharge, laser pulse, flowing the liquid through a Venturi tube), one of the most common techniques is through the application of high intensity sound waves.
In essence, the cavitation process consists of three stages; bubble formation, growth and subsequent collapse. The bubble or bubbles cavitated during this process absorb the applied energy, for example sound energy, and then release the energy in the form of light emission during an extremely brief period of time. The intensity of the generated light depends on a variety of factors including the physical properties of the liquid (e.g., density, surface tension, vapor pressure, chemical structure, temperature, hydrostatic pressure, etc.) and the applied energy (e.g., sound wave amplitude, sound wave frequency, etc.).
It is generally recognized that during the collapse of a cavitating bubble extremely high temperature plasmas are developed, leading to the observed sonoluminescence effect. This phenomena is at the heart of a considerable amount of research as scientists and engineers attempt to both completely characterize the phenomena and find applications for it. Noted applications include sonochemistry, chemical detoxification, ultrasonic cleaning and nuclear fusion.
U.S. Pat. No. 4,333,796 discloses a cavitation chamber comprised of a refractory metal such as tungsten, titanium, molybdenum, rhenium or some alloy thereof. Acoustic energy is supplied to the liquid (e.g., lithium or an alloy thereof) within the chamber by six metal acoustic horns coupled to transducers. The tips of the horns project into the chamber while the rearward portion of each horn is coupled to a heat exchange system, the heat exchange system withdrawing heat generated by the reactions within the chamber. In one disclosed embodiment, the source (i.e., deuterium) is introduced into the cavitation medium through a conduit attached to the top of the chamber, the concentration of the source being controlled by the dissociation pressure over the surface of the host liquid. In an alternate disclosed embodiment, an external processing system with a combination pump and mixer removes deuterium and tritium gases released from the cavitation zone and trapped within the chamber or tritium gases trapped within the Li-blanket surrounding the chamber and then reintroduces the previously trapped deuterium and tritium into the cavitation zone via a conduit coupled to the cavitation chamber. Additional deuterium may also be introduced into the mixer.
U.S. Pat. No. 4,563,341, a continuation-in-part of U.S. Pat. No. 4,333,796, discloses a slightly modified, cylindrical cavitation chamber. The chamber is surrounded by an external heating coil which allows the liquid within the chamber to be maintained at the desired operating temperature. The system is degassed prior to operation by applying a vacuum through a duct running through the cover of the chamber. During operation, the inventor notes that graphite, dissolved in the host liquid metal, is converted to diamond. The diamond-rich host material is removed via an outlet duct adjacent to the bottom of the chamber and graphite-rich host material is removed via an outlet duct adjacent to the upper end of the chamber. Additional host material and graphite are added by lowering rods comprised of the host material and graphite, respectively, into the heated chamber.
U.S. Pat. No. 5,659,173 discloses a sonoluminescence system that uses a transparent spherical flask fabricated from Pyrex®, Kontes®, quartz or other suitable glass and ranging in size from 10 milliliters to 5 liters. The inventors disclose that preferably the liquid within the flask is degassed and the flask is sealed prior to operation. In one disclosed embodiment, the cavitation chamber is surrounded by a temperature control system, thus allowing the liquid within the chamber to be cooled to a temperature of 1° C.
PCT Application No. US02/16761 discloses a nuclear fusion reactor in which at least a portion of the liquid within the reactor is placed into a state of tension, this state of tension being less than the cavitation threshold of the liquid. The liquid preferably includes enriched deuterium or tritium, the inventors citing deuterated acetone as an exemplary liquid. In at least one disclosed embodiment, acoustic waves are used to pretension the liquid. In order to minimize the effects of gas cushioning during bubble implosion, the liquid is degassed prior to tensioning. After the desired state of tension is obtained, a cavitation initiation source, such as a neutron source, nucleates at least one bubble within the liquid, the bubble having a radius greater than a critical bubble radius. The nucleated bubbles are then imploded, the temperature generated by the implosion being sufficient to induce a nuclear fusion reaction.
PCT Application No. CA03/00342 discloses a nuclear fusion reactor in which a bubble of fusionable material is compressed using an acoustic pulse, the compression of the bubble providing the necessary energy to induce nuclear fusion. The nuclear fusion reactor is spherically shaped and filled with a liquid such as molten lithium or molten sodium. A pressure control system is used to maintain the liquid at the desired operating pressure. To form the desired acoustic pulse, a pneumatic-mechanical system is used in which a plurality of pistons associated with a plurality of air guns strike the outer surface of the reactor with sufficient force to form a shock wave within the liquid in the reactor. In one disclosed embodiment, the spherical reactor is coupled to a fluid flow circuit in which a pump and a valve control the flow of fluid. A reservoir containing a fusionable material, preferably in gaseous form, is in communication with the fluid flow circuit. When desired, a bubble of the fusionable material, preferably encapsulated in a spherical capsule, is released from the reservoir and into the fluid flow circuit, which then injects the bubble into a port at the bottom of the chamber.
Co-pending U.S. patent application Ser. No. 11/002,476, filed Dec. 1, 2004, discloses a multi-stage process for degassing cavitation fluid. During the first stage, the cavitation fluid contained within a separate reservoir is degassed using an attached vacuum system. During the second stage, the cavitation fluid is pumped into the cavitation chamber and cavitated. As a result of the cavitation process, gases dissolved within the cavitation fluid are released. The circulatory system provides a means of pumping the gases from the chamber and the vacuum system provides a means of periodically eliminating the gases from the system. As disclosed, the procedure could also use a third stage of degassing in which cavities are formed within the cavitation fluid within the chamber using any of a variety of means. Once formed, the cavities are cavitated, thereby releasing dissolved gases within the fluid which can then be removed using the circulatory system and the attached vacuum system.
A variety of sonoluminescence systems have been designed which typically require degassing. The present invention provides a method and apparatus for efficiently achieving such degassing in a cavitation system.